package study.web.servlet;


import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

/*
* 替换HttpServlet，根据请求的最后一段路径来进行方法分发
* */
public class BaseServlet extends HttpServlet {

    //根据请求的最后一段路径来进行方法分发
    @Override
    protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //1.获取请求路径
        String uri = req.getRequestURI();//  /project123/BrandServlet/selectAll
        //2.获取最后一段路径:方法名
        //从后开始找第一个出现的 /
        int index=uri.lastIndexOf('/');  // index="/selectAll"
        String methodName = uri.substring(index + 1);

        //3.执行方法
        //3.1获取BrandServlet / UserServlet   字节码对象class
        //this 谁调用this，this就指向谁  本方法由UserServlet或BrandServlet调用
        Class<? extends BaseServlet> cls = this.getClass();
        //3.2获取方法Method对象
        try {
            Method method = cls.getMethod(methodName, HttpServletRequest.class, HttpServletResponse.class);
            //3.3执行方法
            method.invoke(this,req,resp);

        } catch (NoSuchMethodException e) {
            throw new RuntimeException(e);
        } catch (InvocationTargetException e) {
            throw new RuntimeException(e);
        } catch (IllegalAccessException e) {
            throw new RuntimeException(e);
        }


    }
}
